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Trouble for Functional Imaging

Over the past year, a couple of articles have been published identifying problems with functional neuroimaging scanners like functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI). Functional neuroimaging looks at what the brain is doing rather than the structure of the brain, at least in theory.

Last year in Nature, an article titled

Perspective: Brain Scans Need a Rethink

discussed how individuals who move their head during functional neuroimaging scans have results that show neural activity similar to the results of individuals with autism. So the question became, is functional neuroimaging actually finding differences in brains of those who have autism, or do people with autism just move more during scans?

In 2013, a team of Harvard and MIT neuroscientists found similar problems with DTI. In the paper,

Spurious Group Difference Due to Head Motion in a Diffusion MRI Study,

researchers discuss how head movements during a DTI scan makes the brain appear abnormal. The authors indicate that there is a way to reduce, but not completely eliminate, these abnormal readings. The authors reported that most studies do not report how much head movement there was.

These papers raise a couple of interesting questions. First, how reliable are previous papers on functional neuroimaging that did not account for head movement? Second, the differences identified in the 2012 and 2013 papers were the same kind of abnormalities detected in neuroimaging studies of individuals who suffered a concussion. So are functional neuroimaging scans actually detecting differences in the post-concussion brain or are they just detecting anomalies like movement?

It looks like DTI needs further study to prove its reliability before it can hit the big stage.